1. Field of the Invention
The present invention relates to an impulse event separating apparatus and method, and, more particularly, to a method of separating an impulse event from a successive sound, and an apparatus to perform the method.
2. Description of the Related Art
An impulse event, that is, an impact sound, is generated by mechanical interaction between objects, and has a short duration and a high intensity. The impact sound occurs suddenly in background sounds which are relatively stable and can be estimated. According to signal processing theory, the impact sound can be modeled into a zero-state impulse response of a linear system.
Examples of impact sounds include a simplex sound, such as the sound made by striking glass with a rod, and a complex sound, such as an explosive sound or the sound made when a coin falls to the floor.
The impact sound generally has an onset stage and an attenuating stage. In the onset stage, the physical event making the impact sound has a short duration and a high intensity. If the onset is detected, the start of the impact sound can be determined.
Generally, an ideal impulse signal is linearly attenuated in the attenuating stage. That is, the energy of a log function substantially has a linear attenuation slope. According to this property, the event can be tracked, and the energy distribution of the impact sound can be calculated.
Since the successive sounds in which the impact sound and the non-impact sound are mixed generally share frequency bands and overlap each other in the time domain, the impact sound must be distinguished from these successive sounds.
Conventional techniques for separating the impact sound include U.S. Pat. Nos. 6,249,749, 6,182,018 and 5,831,936.